Transcript The Effects of Text Messaging On the Driving Performance

The Effects of Text Messaging On the
Driving Performance of Young Novice
Drivers
MUARC: Kristie Young, Simon Hosking &
Michael Regan
NRMA Motoring & Services: John Brown
NRMA Insurance: Pam Leicester
International Conference on Driver Distraction, Sydney, 2-3 June
2005
Overview
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Acknowledgements
Background
Method
Results
Discussion
Conclusions
Next Steps
Acknowledgements
• Ashley Verdoorn and Nebojsa Tomasevic from
MUARC for programming the simulator drives.
• Karen Stephan and Tom Triggs from MUARC for
their design input.
Background
• Approximately 80% of Australians own a mobile
phone.
• 2% of drivers observed using a hand-held phone
in Melbourne (Taylor et al., 2003)
• Survey found that one in six drivers admit to
regularly sending text messages while driving
(Telstra, 2003).
• But….
• Very little research has examined the effects on
driving performance of text messaging.
Previous Research
• Survey of 2000 UK drivers found that text messaging
viewed as most distracting activity a driver can perform.
• Swedish simulator study found that retrieving and
reading text messages reduced reaction times to
hazards and increased driver workload (Kircher et al.,
2004).
• However, Swedish study only examined effects of
receiving text messages, used experienced drivers and
sample size was small (n = 10).
Study Aims
• Aimed to evaluate, using an advanced driving simulator,
the effects of text messaging on the driving performance
of young novice drivers.
• Examined effects of both retrieving and sending text
messages.
• Focused on young novice drivers aged 18 to 21 years
who had held drivers licence for 6 months or less.
Method
• Participants
– 20 drivers aged 18 to 21 yrs (mean age: 19.1 yrs).
– All had held their driver’s licence for 6 months or
less.
– All were familiar with how to send text messages on
a Nokia mobile phone.
• Materials
– Advanced Driving Simulator located at MUARC
– FaceLab eye tracking equipment
– Nokia 6210 mobile phone
Method
• Drives
– 2 identical test drives containing:
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3 car following tasks
Pedestrian and other traffic hazards
Lane Change Task
4 text message episodes per drive
• Instructions
– Drive as close as possible to speed limit
– Stay in right hand lane unless indicated to do otherwise
– Obey road rules
Method
• Procedure
– 5 minute practice drive
– Completed test drive twice
– On one drive text messages were received at events
1,3,4 and 6.
– On other drive text messages were received at events
2,5,7 and 8.
– Above two event orders were designed to minimise
practice effects
– Order of drives counterbalanced across participants
Driving Scene Footage
Questionnaire – subjective results
Pre Drive Questionnaire revealed
• Seven of the 20 participants said they talk
on a hand held mobile - 5 times per week
• Nine of the 20 participants said they read
text messages – four times per week
• Six of the 20 participants said they send
text messages – two per week
Post Drive Questionnaire
• Participant’s subjective mental load was
assessed by the NASA-RTLX scoring system
• Participants rated the task 61/100 on the scale –
moderately high mental workload.
…19 out of the 20 participants believed their
driving performance was worse when receiving
messages.
…all participants believed their driving
performance was worse when sending text
messages.
Results
Definitions: Retrieving – retrieving message and reading it,
Sending – writing message and sending
• Driving Speeds
– No significant differences in mean, maximum & standard
deviation of speed across all driving events
• 3 Car Following Events
– Average gap between driver and lead vehicle was 50% larger
when text messaging
– The average gap between driver and lead vehicle was 138%
more variable when text messaging.
– Minimum gap between the driver and the lead vehicle was
32% larger when text messaging.
Mean & SD Time Headway
7
8
Text
No Text
5
4
3
2
No Text
6
5
4
3
2
1
1
0
0
Mean
Standard Deviation
Retrieving text
Text
7
Time Headway (secs)
Time Headway (secs)
6
Mean
Standard Deviation
Sending text
Minimum
Results – Eyes off Road Time
• The amount of time drivers spent with their eyes off
the road increased by up to 400% when retrieving and
sending text messages.
0.6
Text
No Text
0.4
0.3
0.2
0.1
Red Light
Car
Following 1
Pedestrian
Car
Following 2
Lane
Change 1
Driving Events
Lane
Change 2
Car Turn
Event
Sending
Retrieving
Sending
Retrieving
Sending
Retrieving
Sending
Retrieving
Sending
Retrieving
Sending
Retrieving
Sending
Retrieving
Sending
0
Retrieving
Proportion
0.5
Car
Following 3
Results – Lane Keeping Ability
• Lateral position deviation increased by up to 70% when
sending texts during the traffic light, pedestrian and 2nd
car following events.
0.4
Text
0.25
No Text
0.2
0.15
Text
0.3
No Text
0.25
0.2
Traffic Light
0.35
0.3
Text
No Text
0.25
0.2
0.15
0.15
0.1
Variable Lateral Postion (m)
0.35
Variable Lateral Position (m)
Variable Lateral Position (m)
0.3
Pedestrian
Car Following
Results – Lane Excursion & Changes
• Number of incorrect
lanes changes made
increased by 140%
when retrieving and
sending texts.
200
Number of Lane Excursions
• Drivers made 28% and
63% more lane
excursions when
retrieving and sending
texts, respectively.
190
Text
180
170
No Text
160
150
140
130
120
110
100
Receiving
Sending
Discussion
• Drivers did not attempt to compensate for
being distracted by reducing speed – may
be a result of instructions.
• But, they did compensate by increasing
their following distance.
• Drivers spent a greater amount of time with
their eyes off the road when text
messaging.
Discussion Cont’d
• Drivers’ lane keeping ability and ability to
detect traffic signs and hazards reduced
when text messaging.
• Sending text messages appeared to be
more distracting than reading texts –
generating a response is more cognitively
and physically demanding.
Conclusions
• Retrieving and, in particular, sending text messages
has a detrimental effect on driving performance.
• Text messaging affected drivers’ lane keeping ability,
ability to detect signs and hazards and increases the
amount of time spent not looking at the road.
• Drivers did attempt to compensate for this
degradation in driving performance by increasing
following distance, but not by reducing speed.
• These degradations are likely to greatly increase
crash risk.
Next Steps
• Further research to determine how frequently
drivers are engaging in texting while driving.
• Further research to understand the effect of
text messaging on the driving performance of
other age groups.
• Determine what countermeasures will deter
this risky driver behaviour.